Please refer to my reply in brackets below,
for answer c how to get pattern 15, do we need to work out from p8 unitl p15, (No) is there a short cut method to get the value of unshaded pattern no when there is a total of unshaded squares . (Yes) can you clarifiy (Yes.
(pattern number + pattern number) x (pattern number x pattern number)
pattern 8 ——- (8 + 8) x 16 = 256
900 = 30 x 30 = (15 + 15) x 30)